With Index: colors;background you get the page
Title: Defining Graphics or Colors in the Background of Pages (Watermark)
It does only mention bitmap and color as background. But for Writer, Draw and Impress the new area dialog with Gradient, Pattern and Hatches is already implemented for background of pages. Only Calc uses still the old dialog. The help page needs to be adapted.
Tested in Version: 184.108.40.206.alpha0+
Build ID: 6a59352290a5d05c4236522b56124ac06cd591ad
CPU threads: 4; OS: Windows 6.1; UI render: default;
TinderBox: Win-x86@62-TDF, Branch:MASTER, Time: 2017-03-31_08:37:47
Locale: de-DE (de_DE); Calc: group
Correct file reference:
I think this is a duplicate of bug #96496 though.
*** This bug has been marked as a duplicate of bug 96496 ***